学习日志---8

 MapReduce倒排索引

代码：

MyMapper.java

package dpsy;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

public class MyMapper extends Mapper<LongWritable, Text, Text, Text> {

    @Override
    protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, Text>.Context context)
            throws IOException, InterruptedException {
        // TODO 自动生成的方法存根
        String thisLine=value.toString();
        String words[]=thisLine.split(" ");
        for (String word : words) {
            FileSplit fileSplit=(FileSplit)context.getInputSplit();
            String file=fileSplit.getPath().getName();
            context.write(new Text(word+"&"+file), new Text("1"));
        }
    }

    
    
}

MyCombiner.java

package dpsy;

import java.io.IOException;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class MyCombiner extends Reducer<Text, Text, Text, Text> {

    @Override
    protected void reduce(Text arg0, Iterable<Text> arg1, Reducer<Text, Text, Text, Text>.Context arg2)
            throws IOException, InterruptedException {
        // TODO 自动生成的方法存根
        int sum=0;
        for (Text text : arg1) {
            sum+=Integer.parseInt(text.toString());
        }
        String s[]=arg0.toString().split("&");
        String outKey=s[0];
        String outValue="("+s[1]+":"+sum+")";
        arg2.write(new Text(outKey), new Text(outValue));
    }
    

}

MyReducer.java

package dpsy;

import java.io.IOException;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class MyReducer extends Reducer<Text, Text, Text, Text> {

    @Override
    protected void reduce(Text arg0, Iterable<Text> arg1, Reducer<Text, Text, Text, Text>.Context arg2)
            throws IOException, InterruptedException {
        // TODO 自动生成的方法存根
        StringBuffer outValue=new StringBuffer("");
        for (Text arg : arg1) {
            outValue.append(arg.toString());
        }
        arg2.write(arg0, new Text(outValue.toString()));
    }

    
    
}

MyJob.java

package dpsy;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;



public class MyJob extends Configured implements Tool{
    
    public static void main(String[] args) throws Exception {
        System.setProperty("hadoop.home.dir", "E:\hadoop");
        MyJob myJob=new MyJob();
        ToolRunner.run(myJob, null);
    }
    public int run(String[] args) throws Exception {
        // TODO Auto-generated method stub
        Configuration conf=new Configuration();
        conf.set("fs.default.name", "hdfs://192.168.137.11:9000");
        Job job=Job.getInstance(conf);
        job.setJarByClass(MyJob.class);
        job.setMapperClass(MyMapper.class);
        job.setCombinerClass(MyCombiner.class);
        job.setReducerClass(MyReducer.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(Text.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);
        FileInputFormat.addInputPath(job, new Path("/hadoop/dpsy"));
        FileOutputFormat.setOutputPath(job, new Path("/dpsyResult"));
        job.waitForCompletion(true);
        
        return 0;
    }

}

 结果：